Two-temperature refrigeration control



Aug. 21, 1951 Original Filed Nov. s, 1933 IN V EN TOR.

Glen 7 Ml: f/Zg,

- Patented Aug. 21, 1951 UNITED STATES PATENT OFFICE TWO-TEMPERATUREREFRIGERATION CONTROL Glenn Muflly, Springfield, Ohio 11 Claims. (Cl.82-4) This application is a division of co-pending application SerialNo. 252,291 filed January 23, 1939, now Patent No. 2,407,794 issuedSeptember 1'7, 1946, which is a division of application Serial No.697,124, filed November 8, 1933, now Patent No. 2,145,773 issued January31, 1939.

This invention relates to mechanical refrigerators, and the claims ofthe original application are particularly directed to methods andapparatus for freezing ice, and more particularly to methods andapparatus for causing the ice to free itself from the surface upon whichit has been frozen in order that more ice may be frozen upon the samesurface while the first formed ice is stored for later use.

One of the objects of this invention is to selectively refrigerate oneor more evaporators of a two temperature system.

Another object is the provision of diversion of the refrigerant path inresponse to temperature conditions.

The above being among the objects of the present invention, the sameconsists in certain novel features of construction, combinations ofparts and steps of operation that will hereinafter be described withreference to the accompanying drawing, and then claimed, having theabove and other objects in view.

In the accompanying drawing which illustrates one embodiment of thepresent invention, the valve mechanism is shown in section and otherparts diagrammatically.

Any suitable type of refrigerating mechanism having suitable cyclicoperation and having any suitable type of refrigerant flow controllingde- .vice"may, of course, be adapted for use in connection with thepresent invention, the particular mechanism shown more or lessdiagrammatically at l 9 including a compressor I So driven a-rsuitableelectric motor I91 and discharging -refrigerant therefrom to a condensorl9g from which it is conveyed to an expansion valve which discharges therefrigerant therefrom to one or both of the evaporators II and 38 afterbeing gasified the refrigerant is returned to the suction side of thecompressor l9e.

Any suitable or conventional type of control mechanism may be providedfor controlling the operation of the motor Hi. The particular controlindicated diagrammatically is of the thermostatic type including acontrol bulb l5 secured in contact with the tube 38 so as to preventfrosting of the suction line, a control switch indicateddiagrammatically at l8 and controlled thereby and connected in serieswith 2 the motor 19] and a suitable source of electrical energy.

A special thermostatic valve 26 in the passage \leading from theevaporator ll acts to stop and start refrigeration of evaporator ll onlywithout depending upon cyclic operation of the condensing unit. Thisvalve includes a casing 27 having a cover 23. Intermediate the ends ofthe casing 21 a centrally apertured bowed diaphragm 34 is sealed at itsedges to the casing 27 so as to divide its interior into twocompartments. The diaphragm 34 is of metal and being bowed has thecharacteristic that when flexed over its central plane tends to snapinto bowed position on the other side thereof. The marginal edges of thecentral aperture in the diaphragm 34 are bent upwardly to form a valveseat 35 and positioned above the valve seat 35 is a valve element 36which is fixed and sealed to a pin 32 extending centrally through thecentral aperture in the diaphragm 34. Below the diaphragm the pin 32 hassecured thereto a serrated crown stop 33 which will permit flow ofrefrigerant between it and the diaphragm 34 even though they are incontact with each other.

Although any suitable temperature'responsive element such as a bellows,bi-metallic element or the like may be employed to operate the valve 35,as a matter of illustration only I have shown a strap 29 formed of amaterial having a high coeflioient of expansion, such as zinc, securedat its opposite ends to the cover 28 and at its center to the pin 32.The cap 28 is provided with an upstanding central tubular boss in whichis threadably received a, plug 3| between which and the strap 29adjacent the upper end of the pin 32 a coil spring 30 is maintainedunder compression, the force of which may be varied by adjusting theplug 3|. With this construction the liquid refrigerant from theexpansion valve 20 is divided, one partthereof passing through theevaporator II and discharging therefrom into the valve above thediaphragm 34, while the remainder of the refrigerant from the expansionvalve may pass through a coil such as 31 to the tube 38. The interiorofthe valve 28 below the diaphragm 34 is connected to the suction tube38 beyond the coil 31. The coil 31 is formed of a tube having a smallcapillary passage designed to restrict the flow of vapor, while allowingthe desired amount of liquid refrigerant to pass through it. In additionthere is some additional evaporator surface associated with the tube 38.

Assuming the valve to be in the position indicated and the refrigeratingmechanism as being active, liquid refrigerant from the expansion valve20 will fiow through the evaporator II and into the upper end of thevalve 26 and then between the valve 36 and the valve seat 35 into thelower part of the casing 21 and then to the tube 38, causing evaporatorsII and 38 to be refrigerated. Under such conditions as the refrigerationof H proceeds the refrigerant flowing into the valve 26 will becomecolder, causing the strap 29 to contract against the force of the spring30 until such time as the pin 32 and consequently the stop member 33will have been raised sufficiently to cause the diaphragm 34 to snapupwardly into contact with the valve 36 and thereby shut off the flow ofrefrigerant through the valve 26 and evaporator H. As soon as thisoccurs all of the refrigerant fiowing through the expansion valve 20will be forced through the coil 31 to the tube 38 and, accordingly, theevaporation of refrigerant in II will stop. During this period thethermally responsive strap 29 will expand, due to the rise oftemperature, and the valve 36 will push downwardly on its seat 35 underthe force of spring 30. This force exerted upon the diaphragm 34 willincrease gradually under the rising temperature within the space abovethe diaphragm 34 until the diaphragm snaps downwardly, opening the valveand reestablishing the process of refrigerating the evaporator H.

The refrigerant has but one path back to the condensing unit while thevalve 36 is closed, but when it is open the refrigerant flows throughtwo paths that are connected in parallel.

Formal changes may be made in the specific embodiment of the inventiondescribed without departing from the spirit or substance of the broadinvention, the scope of which is commensurate with the appended claims.

What I claim is:

1. In a refrigerating system, two evaporators,

liquid flow means including a pressure reducing device of the vapor-locktype and another pressure reducing device, connecting means for seriesflow of refrigerant liquid through both said devices to one of saidevaporators, connecting means for flow of refrigerant liquid to theother of said evaporators through one only of said devices, therebyproducing less than the total pressure reducing effect of the two saiddevices, and a thermally actuated valve for regulating the flow ofrefrigerant to limit operation of one of said evaporators and tosimultaneously cause an increased fiow of liquid refrigerant to theother of said evaporators.

2. In a refrigerating system. a pair of evaporators connected in saidsystem, first and second liquid flow control devices providing two stepsof pressure reduction in series, conduits associated with saidcontrolling devices to feed liquid refrigerant to one of saidevaporators at a relatively high evaporating pressure through one ofsaid devices and to the other at a relatively lower pressure throughboth of said devices, one of said devices comprising a vapor-lockrestrictor, unitary flow-shifting device for shifting cooling effectfrom one of said evaporators to the other by reducing refrigerantevaporation in one and increasing refrigerant evaporation in the other,a thermostatic control device responsive to a temperature effectassociated with one of said evaporators to actuate said flow-shiftingdevice, and a control device responsive to a temperature changeassociated with the other evaporator for stopping said system.

3. In a refrigerating apparatus, a plurality of evaporators, first andsecond refrigerant liquid control devices providing two steps ofpressure reduction, one of said steps being effected by a device forminga constantly open passage of restricted diameter in proportion to itslength, and a flow-shifting device for diverting refrigerant liquid flowrelative to the device providing one of said steps of pressurereduction, said shifting device being so constructed and arranged as tocause an evaporator already cooled by refrigerant flowing through onlyone of said steps to continue operation with refrigerant liquid flowinto it through both said steps of pressure reduction.

4. In a refrigerating system charged with a volatile refrigerant, twoevaporators, refrigerant pressure reducing means including two sections,at least one of said sections comprising means forming a constantly openpassage of small diameter, means connecting a first of said evaporatorsto receive liquid refrigerant through both said sections, meansconnectin a second of said evaporators to receive liquid refrigerantthrough one only of said sections, and a control device energized inresponse to changes of temperature to provide at one time for cooling ofboth said evaporators with refrigerant liquid flowing through one onlyof said pressure reducing sections and mostly evaporating in one of saidevaporators and to-provide at another time for cooling the other of saidevaporators with refrigerant liquid flowing through the other of saidpressure reducing sections and mostly evaporating in the last said otherevaporator.

5. In a refrigerating system charged with a volatile refrigerant,refrigerant pressure reducing means including two sections, at least oneof said sections comprising means forming a constantly open passage ofsmall diameter, an evaporator connected to receive liquid refrigerantthrough both said sections, another evaporator connected to be suppliedwith liquid refrigerant through only one of said sections, meansenergized by a change of temperature for substantially stopping theevaporation of refrigerant in one of said evaporators and increasing thefiow of liquid refrigerant to the other said evaporator, and meansresponsive to another change of temperature for controlling said system.

6. In a refrigerating system employing a volatile refrigerant, acondensing unit, an expansion device for reducing the pressure of saidrefrigerant liquid to allow it to evaporate, a second expansion devicefor reducing refrigerant pressure to a lower point for evaporation at alower temperature, a first evaporator connected to receive liquidrefrigerant from the first said device, a second evaporator connected toreceive liquid refrigerant from the second said device and alsoconnected in series with the first said evaporator, a control mechanismfor substantially stopping the evaporative effect produced in the firstsaid evaporator during operation of said condensing unit, and means forsupplying energy to actuate said control mechanism in response to achange of temperature, said system and control mechanism being soconstructed and arranged as to cause an increase in the flow of liquidrefrigerant to the second of said evaporators simultaneously with thestopping of said evaporative effect in the first said evaporator andthereby cause the second said evaporator to become more active.

- '7. The method of cooling an evaporator by selectively feeding avolatile refrigerant to it' ration and temperature of evaporation in theevaporator, employing the vapor-lock method to regulate refrigerant flowto the evaporator durin at least one of said periods, withdrawingrefrigerant vapor from said evaporator, condensing it and returning itto repeat the circuit, which circuit is confined to a pair ofalternative paths of flow.

8. In a refrigerating system employing a volatile refrigerant, apressure imposing element, a

condenser, first and second pressure reducing devices connected inseries, one of said devices being of the vapor-lock type, an evaporatorconnected to receive liquid refrigerant after flowing through both ofsaid reducing devices, a branch outlet connection for refrigerantleading from the first of said pressure reducing devices, anotherevaporator connected to receive liquid refrigerant from said outletafter it has passed through the first one only of said pressure reducingdevices, and means for controlling refrigerant flow through the lastsaid evaporator, said pressure imposing element being connected towithdraw vaporized refrigerant from both said evaporators.

9. In a refrigerating system employing a, volatile refrigerant, apressure imposing element, a condenser, first and second pressurereducing devices connected in series, an evaporator connected to receiveliquid refrigerant after flowing through both of said reducing devices,a branch outlet connection for refrigerant leading from the first ofsaid pressure reducing devices, another evaporator connected to receiveliquid refrigerant from said outlet after it has passed through thefirst one only of said pressure reducing devices, and means forcontrolling refrigerant flow through the last said evaporator.

10. In a refrigerating system charged with a volatile refrigerant, apressure imposing element, a condenser, liquid refrigerant controlapparatus providing two stages of pressure reduction, a pair ofevaporators, refrigerant conduits for by-passing one of said evaporatorsand feeding the other evaporator with liquid refrigerant through bothsaid stages of pressure reduction and alternatively for by-passing oneof said stages of pressure reduction and feeding both of saidevaporators through only one stage of pressure reduction, and a valvearranged to open and close a port in one of said conduits to control theoperation of one of said evaporators in response to temperature changes.

11. In a refrigerating system employing a volatile refrigerant, twoevaporators connected in series, a. first pressure reducing devicearranged to feed liquid refrigerant to the first of said evaporators ata moderate evaporating pressure, a conduit leading from the first saidpressure reducing device and forming a by-pass around said firstevaporator, 9, second pressure reducing device in said by-pass arrangedto feed the second of said evaporators at a lower evaporating pressure,a valve arranged to stop flow through one of said evaporators while theother continues to operate, and thermally responsive means for supplyingenergy to actuate said valve.

GLENN MUFFLY.

REFERENCES CITED The following references are of record in the file ofthis patent:

Philipp Oct. 5, 1937 Certificate of Correction Patent No. 2,565,145August 21, 1951 GLENN MUFFLY It is hereby certified that error appearsin the printed specification of the above numbered patent requiringcorrection as follows:

Column 3, line 42, after flow insert controlling;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOflice.

Signed and sealed this 18th day of December, A. D. 1951.

THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents.

